webcit-ng/server/webserver.c

   1 // webserver.c
   2 //
   3 // This module handles the task of setting up a listening socket, accepting
   4 // connections, and dispatching active connections onto a pool of worker
   5 // threads.
   6 //
   7 // Copyright (c) 1996-2022 by the citadel.org team
   8 //
   9 // This program is open source software.  Use, duplication, or disclosure is subject to the GNU General Public License v3.
  10
  11 #include "webcit.h"                     // All other headers are included from this header.
  12
  13 int num_threads_executing = 1;          // Number of worker threads currently bound to a connected client
  14 int num_threads_existing = 1;           // Total number of worker threads that exist right now
  15 int is_https = 0;                       // Set to nonzero if we are running as an HTTPS server today.
  16 static void *original_brk = NULL;       // Remember the original program break so we can test for leaks
  17
  18
  19 // Spawn an additional worker thread into the pool.
  20 void spawn_another_worker_thread(int *pointer_to_master_socket) {
  21         pthread_t th;           // Thread descriptor
  22         pthread_attr_t attr;    // Thread attributes
  23
  24         // set attributes for the new thread
  25         pthread_attr_init(&attr);
  26         pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
  27         pthread_attr_setstacksize(&attr, 1048576);      // Large stacks to prevent MIME parser crash on FreeBSD
  28
  29         // now create the thread
  30         if (pthread_create(&th, &attr, (void *(*)(void *)) worker_entry, (void *) pointer_to_master_socket) != 0) {
  31                 syslog(LOG_WARNING, "Can't create thread: %s", strerror(errno));
  32         }
  33         else {
  34                 ++num_threads_existing;
  35                 ++num_threads_executing;
  36         }
  37
  38         // free up the attributes
  39         pthread_attr_destroy(&attr);
  40 }
  41
  42
  43 // Entry point for worker threads
  44 void worker_entry(int *pointer_to_master_socket) {
  45         int master_socket = *pointer_to_master_socket;
  46         int i = 0;
  47         int fail_this_transaction = 0;
  48         struct client_handle ch;
  49
  50         while (1) {
  51                 // Each worker thread blocks on accept() while waiting for something to do.
  52                 // We don't have to worry about the "thundering herd" problem on modern kernels; for an explanation see
  53                 // https://stackoverflow.com/questions/2213779/does-the-thundering-herd-problem-exist-on-linux-anymore
  54                 memset(&ch, 0, sizeof ch);
  55                 ch.sock = -1;
  56                 errno = EAGAIN;
  57                 do {
  58                         --num_threads_executing;
  59                         syslog(LOG_DEBUG, "Additional memory allocated since startup: %d bytes", (int) (sbrk(0) - original_brk));
  60                         syslog(LOG_DEBUG, "Thread 0x%x calling accept() on master socket %d", (unsigned int) pthread_self(),
  61                                master_socket);
  62                         ch.sock = accept(master_socket, NULL, 0);
  63                         if (ch.sock < 0) {
  64                                 syslog(LOG_DEBUG, "accept() : %s", strerror(errno));
  65                         }
  66                         ++num_threads_executing;
  67                         syslog(LOG_DEBUG, "socket %d is awake , threads executing: %d , threads total: %d", ch.sock,
  68                                num_threads_executing, num_threads_existing);
  69                 } while ((master_socket > 0) && (ch.sock < 0));
  70
  71                 // If all threads are executing, spawn more, up to the maximum
  72                 if ((num_threads_executing >= num_threads_existing) && (num_threads_existing <= MAX_WORKER_THREADS)) {
  73                         spawn_another_worker_thread(pointer_to_master_socket);
  74                 }
  75
  76                 // We have a client.  Do some work.
  77
  78                 // Set the SO_REUSEADDR socket option
  79                 i = 1;
  80                 setsockopt(ch.sock, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
  81
  82                 // If we are an HTTPS server, go crypto now.
  83                 if (is_https) {
  84                         starttls(&ch);
  85                         if (ch.ssl_handle == NULL) {
  86                                 fail_this_transaction = 1;
  87                         }
  88                 }
  89                 else {
  90                         int fdflags;
  91                         fdflags = fcntl(ch.sock, F_GETFL);
  92                         if (fdflags < 0) {
  93                                 syslog(LOG_WARNING, "unable to get server socket flags! %s", strerror(errno));
  94                         }
  95                 }
  96
  97                 // Perform an HTTP transaction...
  98                 if (fail_this_transaction == 0) {
  99                         perform_one_http_transaction(&ch);
 100                 }
 101
 102                 // Shut down SSL/TLS if required...
 103                 if (is_https) {
 104                         endtls(&ch);
 105                 }
 106                 // ...and close the socket.
 107                 //syslog(LOG_DEBUG, "Closing socket %d...", ch.sock);
 108                 //lingering_close(ch.sock);
 109                 close(ch.sock);
 110                 syslog(LOG_DEBUG, "Closed socket %d.", ch.sock);
 111         }
 112 }
 113
 114
 115 // Start up a TCP HTTP[S] server on the requested port
 116 int webserver(char *webserver_interface, int webserver_port, int webserver_protocol) {
 117         int master_socket = (-1);
 118         original_brk = sbrk(0);
 119
 120         switch (webserver_protocol) {
 121         case WEBSERVER_HTTP:
 122                 syslog(LOG_DEBUG, "Starting HTTP server on %s:%d", webserver_interface, webserver_port);
 123                 master_socket = webcit_tcp_server(webserver_interface, webserver_port, 10);
 124                 break;
 125         case WEBSERVER_HTTPS:
 126                 syslog(LOG_DEBUG, "Starting HTTPS server on %s:%d", webserver_interface, webserver_port);
 127                 master_socket = webcit_tcp_server(webserver_interface, webserver_port, 10);
 128                 init_ssl();
 129                 is_https = 1;
 130                 break;
 131         default:
 132                 syslog(LOG_ERR, "unknown protocol");
 133                 ;;
 134         }
 135
 136         if (master_socket < 1) {
 137                 syslog(LOG_ERR, "Unable to bind the web server listening socket");
 138                 return (1);
 139         }
 140
 141         syslog(LOG_INFO, "Listening on socket %d", master_socket);
 142         signal(SIGPIPE, SIG_IGN);
 143
 144         worker_entry(&master_socket);   // this thread becomes a worker
 145         return (0);
 146 }